Motor Vehicle Emissions Budgets (SIP Transportation Conformity)

Current understanding

To be populated as evidence accumulates.

Evidence log

• 2026-10-19 — Approval and Promulgation of Implementation Plans-Pinal County (Part); West Pinal, AZ PM10 Nonattainment Area; Moderate Area, Serious Area, and Section 189(d) Plan for Attainment of the 24-Hour PM10 Standard: cross-connection with pm10-naaqs-nonattainment-areas: West Pinal PM10 SIP approval would establish on-road motor-vehicle emissions budgets used in transportation conformity determinations. (novelty: 2)
• 2026-10-29 — Air Plan Approval; California; Reasonable Further Progress Plan for the Coachella Valley Ozone Nonattainment Area: cross-connection with ozone-naaqs-area-designations: Coachella Valley RFP plan sets motor vehicle emissions budgets used for transportation conformity under the 2008 ozone NAAQS. (novelty: 2)
• 2026-09-23 — Air Plan Approval; North Carolina; Charlotte-Rock Hill Area Maintenance Plan for the 2008 8-Hour Ozone NAAQS: cross-connection with ozone-naaqs-area-designations: Charlotte-Rock Hill second maintenance plan sets NOx and VOC motor vehicle emissions budgets that govern transportation conformity determinations through 2035. (novelty: 2)
• 2026-10-01 — Approval of Implementation Plans for Air Quality Planning Purposes; State of Nevada; Truckee Meadows Second 10-Year Maintenance Plan for the 1987 PM-10 Standard: Truckee Meadows second 10-year PM-10 maintenance plan includes revised motor vehicle emissions budgets that local MPOs must use for transportation conformity determinations once EPA finalizes approval. (novelty: 2)
• 2026-09-14 — Approval and Promulgation of Implementation Plans; California; San Joaquin Valley, Revisions to Motor Vehicle Emissions Budgets for Ozone: EPA finalized approval of updated San Joaquin Valley motor vehicle emissions budgets for ozone-forming pollutants (NOx and VOC), replacing prior budgets that regional transportation plans and conformity determinations must stay within. (novelty: 2)

Open questions

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